1. Field of the Invention
The invention pertains to a hydrodynamic retarder with a first blade wheel, acting as a rotor blade wheel, and with a second blade wheel, concentric to the first, acting as a stator blade wheel, which together form a hydrodynamic circuit and are grouped around a common axis of rotation.
2. Prior Art
A hydrodynamic retarder with a first blade wheel, acting as a rotor blade wheel, and with a second blade wheel, concentric to the first, acting as a stator blade wheel, is known from EP 1 305 535 B1. These two blade wheels form a hydrodynamic circuit and are grouped around a common axis of rotation, wherein each blade wheel consists of a base body and a blading with a plurality of blades permanently attached to the base body, each blade being connected to receptacles in the base body by blade tangs.
Retarders of this type suffer from the basic problem that cavitation occurs as a result of the high-speed infeed of fresh fluid into the hydrodynamic circuit. This can cause damage to the blading of the stator blade wheel, usually in a radially outer area of the blades. For this reason, all of the blades on the stator blade wheel have a bevel in the radially outer area, extending back from the flow edge, i.e., the edge which faces the rotor blade wheel. In the case of a blade design of this type, however, only the radially outermost end of the blade is protected from cavitation, not the part of the blade most affected by it, namely, the area radially inside this radially outermost end. Blades machined in this way are not only more expensive than conventional blades but are also seated less reliably in the base body of the blade wheel in the radially outer area because of the reduced length by which they can be fitted into the base body. These blades, furthermore, are used around the entire circumference of the stator blade wheel, even though the problem of cavitation is limited primarily to the area where fresh fluid enters the hydrodynamic circuit or to the area closely adjacent to this entry area.